Data from: Pupil dilation as an index of preferred mutual gaze duration

Most animals look at each other to signal threat or interest. In humans, this social interaction is usually punctuated with brief periods of mutual eye contact. Deviations from this pattern of gazing behaviour generally make us feel uncomfortable and are a defining characteristic of clinical conditions such as autism or schizophrenia, yet it is unclear what constitutes normal eye contact. Here, we measured, across a wide range of ages, cultures and personality types, the period of direct gaze that feels comfortable and examined whether autonomic factors linked to arousal were indicative of people's preferred amount of eye contact. Surprisingly, we find that preferred period of gaze duration is not dependent on fundamental characteristics such as gender, personality traits or attractiveness. However, we do find that subtle pupillary changes, indicative of physiological arousal, correlate with the amount of eye contact people find comfortable. Specifically, people preferring longer durations of eye contact display faster increases in pupil size when viewing another person than those preferring shorter durations. These results reveal that a person's preferred duration of eye contact is signalled by physiological indices (pupil dilation) beyond volitional control that may play a modulatory role in gaze behaviour.

多数动物会通过对视传递威胁或意图。对人类而言，此类社交互动通常会穿插短暂的双向目光接触。偏离该凝视行为模式的表现通常会令个体产生不适感，同时也是自闭症、精神分裂症等临床病症的标志性特征之一，但目前学界尚未明确何为正常的目光接触模式。本研究在覆盖广泛年龄层、文化背景与人格类型的群体中，测量了令个体感到舒适的直接凝视时长，并探究了与唤醒状态相关的自主神经因素是否能够反映个体偏好的目光接触量。研究结果令人意外：个体偏好的凝视时长并不受性别、人格特质或外貌吸引力这类基础特征影响。但我们确实观察到，反映生理唤醒状态的细微瞳孔变化，与个体感到舒适的目光接触量存在显著相关性。具体而言，偏好更长时长目光接触的个体，在观察他人时瞳孔尺寸的增长速度快于偏好较短时长目光接触的个体。上述研究结果表明，个体偏好的目光接触时长可通过不受意志控制的生理指标（瞳孔扩张）进行体现，这类指标可能在凝视行为中发挥调节作用。